Furnace draft automatic release



July 8, 1952 R. G. HUGHES FURNACE DRAFT AUTOMATIC RELEASE 2 SHEETSSHEET 1 Filed May 10, 1949 INVENTOR- Fpy 6 HUGHES July 8, 1952 R. G. HUGHES FURNACE DRAFT AUTOMATIC RELEASE Filed May 10, 1949 Z7 FiJI IEA- 2 SHEETS-SHEET 2 INVENTOR. F0 Y G. Hue/15s A T'T'OH/VE YS deviceshown in Figures3and/i; 1

Patented July 8, 19521. 5115.1 p I intesti were n;

It is among the objects of the' in'vention to ro; vide an improved automatic release devi'c'efof smali'size and-light weight whichcanhe'directly connected-into a tension strand, suchasfa furnace draft-control chain a or cable, which is auto- 'matically actuated upon failure of power to the draft-controlling motor or upon-overheatin'g' of the furnace, to immediately release the chain or cable and permit the draft to close, which is simple and durable in construction and extremelyf economical to manufactuieso that'it can be sold at a nominal cost either a'sstandard equipment withnew furnace-control systems; o'r--as"an a'c-' cessory 'to be added-to an ex'isting system, and which'iseasy to install, requires to material modification of 'a control system in which it is incorporated, is not subject to malfunctioning in use, and provides a positive safety control for preventingfurnace overheating, and for sim'ilarpurposes. Other obj-ects' and advantages willbecomel apw parent from a consideration of the following dea scriptio'nand the appended'claims in conjunction with the accompanyingdrawings, wherein:

Figure 1 is a diagrammatic illustration of'a furmace-control .systemshowing the application thereto of an automatic releaseillustrative of the invention; i I

Figure 2 is a diagrammatic view of a furnace charms.

j- Application'May 10,1949,s riam --92hs9f i, wig'fizlj.

l3 ipivotallyiconnected' atits upper edge .-"to- .the

I clean-out door 12 by suitable 1 hinge M, c The.

control system different 'fromthat illustrated in Figure l, and showing the application thereto of an automatic draftrelease illustrative of the invention;

- Figure 3-is a rear'elevation of the automatic draft-releaseidevice of the invention Figure 4 'is' a front: elevation of the draft-release. device illustrated in Figure3; Figure 5 is a side elevation of the-draft-release Figure 6 is a longitudinal cross-section on-the 1ine6,.6ofFigure4;.-

Figure 7 is a rear elevationof a somewhat. mod-' ified form of automatic release device.;- 1 Figure. Bis a front elevation ofthe device illus-.

tratedinFigure'l;

.Figure 9 isa longitudinal cross-section: on the 1ine9.-;9.of FigureBg 1: 1;; l

iWithcontinued reference to the drawings; and particularly to Figures 12and'2, the=numeral ll) generally indicates afurnace coverwor housing havingithe'rein a fuel re'ceiving door It a'ndan ash pit or clean-out door l2 provided with a draft opening therein controlled by a draft door closing-thedraft doorm draft-doorclll' has an arm [5 projecting from one end thereof at its lower edge. for opening: and

, Asthe furnace may he of' conventional construction, a further-description is. considered unnecessary. for the purposes of the spresentzdis closure Opening of the draft door '15. will permit a draft of air into the furnace under the furnace grates to promote the combustion of. fuel in the furnace, and closing of the draft door will cutoff this flow of air retarding..combustion of fuel in the furnace and causing the furnace to v c ool..:.,- The amount of heat supplied by. the fur nace maythus be controlledbyvariably opening theqdraft door [3, the furnace generating itsm'axe imum heat output-when the draft door is side open and generating a minimum amount of heat whentheidraft door is fully closed.: In t.he :arrangement shown. in Figure. l, .the draftregulating door. [3 is controlledby a ,con-j ventional draft-regulating, electric motor 16 opera ated from a step-down transformer l1 under'the control of a room thermostat l8.

{this system operates entirely satisfactorily as long as there is no; interruption to .the electric power supplied to the motor. I 6 through the-transformer ll'and thermostat l8; If the power'sh ould accidentally fail, however, while thefurnacefis in operation, the motor. l6 may stopina position in which the draft-regulating door l3 ,i'sleft open. With this door open, the furnace will .continueto heat and frequently-under these conditions, the furnace reaches such a high temperaturev as to damage the furnace, or cause a fire in the buildinginwhich' thefurnace is installed. Themotor [6 is connected to the draft-regulating door l3 through the intermediacy of a flexible strand, such as the chain generally indicated at I9; and to avoid the contingency of the furnace overheating in the event of power failure to the motor It; the present invention contemplates the interposition .of the automatic release device, gener ally'indicated at 20, in the chain I9 to release the tension on the chain and'permit the draftregulating door to close upon failure of the sup- 3 venient position in the house above the location at which the furnace is installed. With such a manually-operated control the draft regulation may be forgotten and the draft-regulating door left open, particularly during the absence of the occupants from the house, in which case the furnace may seriously overheat, damaging the furnace, or even causing a fire in the building. The invention contemplates the interconnection of an automatic release device, generally indicated at 20', in the chain l9 to obviate such a contingency. The device 20' is substantially the same as the device 20, but operates in a slightly different manner because of the lack of a normal supply of electric current to the draft-regulating system, no current supply being necessary in the case of the manually-operated control system. R

In the arrangement illustrated in Figure 2, a step-down transformerZZ is'provided, and one end of the low-voltage side of this transformer is'iconnected to one side of .a temperature-responsive switch 23 mounted on the furna'celll. The opposite side of the switch is connectedjto .one side of the automatic release device 20; and .the other side ofthis device is connected tothe other end of. the lowevoltage sideof the. transformer, so that,v when the temperature of the .iurnace exceeds a predetermined valueand the tempera-, tore-responsive switch 23 closes, the device 20" y will be actuated to lengthen the chain. [9 sufliciently to close the draft-regulating door l3.

Obviously, this device could be operated Just as well by having the switch '23 normally closed and arranged to open when the furnace temperature reaches a predetermined degree, thereby interrupting the supplyof electrical energy to the device 20, and thus causing the device to operate and lengthen the chain to close the furnace draftregulating door. a

The automaticrelease device generally desig--' 'nated at 20; in Figure 1 is illustrated in detail in Figures 3 to 6, inclusive, to which reference may now "be 'had for a detailed "description of the devige V. I V

The device 20 comprises-an elongated; metal plate or strap 25 provided with an arcuatelyrounded 'end 28 and anaperture 2'! near such rounded end to receive one end of the chain [9, or other flexible strand, into which the device is connected. Near its opposite end the platel isiolded along its longitudinal center line to provide a pair of spaced-apart, substantially parallel ears 28, which ears are provided with registering apertures near the corresponding end of the plate.

.Near the rounded'end 26, th'e plate is provided with a U -shaped bend 29 forming a magnet-receiving recess and anele'ctromagnet 30 is positioned in this'recess and secured atone end to thebight of the U -shaped bend. 233, the opposite end of the magnet being substantially flush with the portions of the plate at oppositesides ofjthe The magnet 3a is of conventional construction, and of,low-voltagerequirements, and is electrically connected with the transformer, ll of Figure '31, or. .the transformer: 2250f Figure 2 in a-manner, to -bee energized by the current output of theparticula'r transformer. g

A lever 3| in the form of' an elongated, ben wire having an eye-2'2 at one end is pivotally connected to the plate 25 by meansof a'suitable pivot pin or bolt 33 extending-through the apertures-in the lugs ZS-and through ;the,eye32. of thelever. This lever is swingable between. a position fin which it issuperposed relative to theplate 25'and a position at which it extends outwardly from 'the end of the plate to whichit is pivotally connected.

A link 34 is slidably mounted on the lever 3! for connection to an end of the chain I9 opposite the end connected to the plate by the aperture 21.

When the lever is held to its position superposed upon the plate 25,.asillus trated in Figures 3, 4 and 5, the chain 49 is .of'normal length and held under tension, but when the 'lever is released and swings to the position illustrated in Figure 6, the chain is lengthened sufiiciently to permit the draft-regulating door of the furnace to close. A ring stop is secured on the lever near the free end of the latter to limit movement I releasably hold the lever 31 inpo sition superposed on the plate 25.; This trigger 36 comprisesa fiat plate notched atone end to provide three spaced; apart tines 31 38 and -39. I Thetwo outside tines 3'! and 39 arebentsubstantially at right angles to the remainderof'the trigger .plateand are pivotally received inrespective notches AOand 4| provided in the-sideedges'oi theplate' iE'to pivotally mount. the trigger onthe plate. :The metal tine or tongue'fill is ben t; first substant'ially to the direction of -the outside tines iland 3'9, and is then reg-curved to extend substantially parallel 1 to the major portion of the-tr igger plate. This tongue extendsthrough a' irectangular aperture 42 provided in the plate '25-between "the notches 40 .and {H and is so positioned' that outer end overlies the adjacent end of the lever 3|,1as-c1ear- F ly illustrated in Figure 5 when the trigger plate is in contact near its endspposite the tines with the core 43 of the electromag'net. With this arrangement, as long as' the electromagnet '30 is energized and, holdsthe trigger member 36 against its core, as illustrated in Fig; ure 5, the lever 31 will be locked-in position-superposed relative to the plate ii, and the length of thechain ld w ill be maintained. at-a value to op-i era-te the draft-regulating door1l3. In the event of power failure to the electromage net3ll, the triggerflfi is released toswing downwardly by gravity fromthe position: illustrated in Figure 5 to thegpos'ition illustratediin Figure 6, thereby releasing the *free' end of the driver 3 I .so that thelevercan swingaway from -.the:p1'ate $25 to lengthen the chain 159 in th'e manner described abovei: H v In the arrangement illustrated in- Figures 7,8 and 9, the construction ;is; the sametas. that illustrated in Figures 53 to -6;;incl'usive, and described above, except that in the forni illustrated in Figures 7, 8 and 9, a slightly mo'dified' lever 34" and a slightly modified trigger. res-here used :so that the device will trip when. the solenoi'd ell is energized rather than when .theilsolenoid-fis de-energized; as described above an connection with'Figuresifito 6., inclusive.

this arrangement "the'lever 3:1"; is providedon its free 'end -with-.a. .re-curvedihook 414' and the metal: tine or tongue 38.. oiI-thei1trigger is curved near its outer end in a direction toward instead of away from the major portion of the trigger, so that the outer end of this tongue engages in the hook 44 to latch the lever 3! in position superposed relative to the plate 25 when the trigger is disposed at its maximum distance away from the core 63 of the solenoid. When the solenoid is energized and attracts the free end of the trigger, the tongue 38 is released from the hook M of the lever 31 to free the lever so that the lever will swing downwardly to a position in which it extends outwardly from the end of the plate 25 to which it is pivotally connected, thereby lengthening the chain 9 to close the draft-regulating door of the furnace.

If desired, a tension spring 45 may be connected at one end to a tongue 45 struck out from the trigger 36', and at its opposite end to a tongue 41 struck out from the plate 25 to assist the force of gravity in holding the trigger 38' away from the core of the electromagnet 3B.

As explained above, the form of the device shown in Figures 3 to 6, inclusive, may be used in either of the arrangements shown in Figures 1 and 2, provided that in the arrangement shown in Figure 2, the switch 23 remains closed during normal operation and opens only in response to furnace temperature above a predetermined value. The slightly modified form of device shown in Figures 7, 8 and 9 is designed to save electrical energy in that it operates with the switch 23 normally open and closing upon being subjected to furnace temperature above the predetermined value.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are, therefore, intended to be embraced therein.

I claim:

1. An automatic release device comprising an elongated, flat plate having near one end an aperture for attaching one end of a tension strand thereto, an electromagnet carried by said plate adjacent said one end, said plate having at its opposite end a formation providing a pair of spaced-apart, apertured ears, a lever pivotally connected at one end to said ears, a ring slidable on said lever for attaching an end of a tension strand to the latter, and a trigger pivotally mounted near one end on said plate intermediate the length of the latter and engageable with the free end of said lever to releasably hold the latter in superposed relationship toi said plate, said trigger being movable in response to a change in the energization of said electromagnet to release said lever for swinging movement to a position in which it extends outwardly from the end of said plate to which it is pivotally connected, to thereby increase the length of a strand connected to said plate and said ring, said lever comprising an elongated member having a pivot-pin-receiving eye at its end pivotally connected to said ears, and said trigger comprising an elongated plate structure having on its end pivoted to said plate a tongue engageable with the free end of said lever, said lever and said trigger being disposed at respectively opposite sides of said plate and said plate having an aperture for the projection of said trigger tongue therethrough to engage said lever.

2. An automatic release device comprising an elongated flat plate having near one end an aperture for attaching one end of a tension strand thereto, an electromagnet carried by said plate adjacent said one end, said plate having at its opposite end a formation for the pivotal attachment of a lever to said plate, a lever pivotally connected to one end to said formation, a ring slidable on said lever for attaching an end of a tension strand to the latter, and a trigger pivotally mounted near one end on said plate intermediate the length of the latter and engageable with the free end of said lever to releasably hold the latter in superposed relationship to said plate as long as said electromagnet is energized, said trigger being movable in response to de-energization of said electromagnet to release said lever for swinging movement to a position in which it extends outwardly from the end of said plate to which it is pivotally connected to thereby increase the length of a strand connected to said plate and said ring, said lever comprising an elongated member pivotally connected at one end to said formation and said trigger comprising an elongated plate structure having on its end pivoted to said plate a tongue engageable with the free end of said lever, said lever and said trigger being disposed at respectively opposite sides of said plate and said plate having an aperture for the projection of said trigger tongue therethrough to engage said lever, and a ring stop on said lever near the free end of the latter.

ROY G. HUGHES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Kimball May 1, 1934 

